1. Field of the Invention
The present invention relates generally to asymmetric disulfides, and more specifically to therapeutic compositions comprised of asymmetric disulfides, said asymmetric disulfides providing a desired therapeutic activity. Preferably, the asymmetric disulfides of the present invention interact, inhibit or interfere with cellular redox systems.
2. Background of the Related Art
Cellular redox systems are important to normal cellular activity. Cells maintain an intracellular environment that is reducing in the face of a highly oxidizing extra-cellular environment. Regulated alterations in the intracellular redox state (redox signaling) can modulate cellular activity, including activities such as DNA synthesis, enzyme activation, selective gene expression, cell cycle regulation, cell growth, and programmed cell death.
One of the more important consequences of intracellular redox signaling is a change in the oxidative state of select cysteine residues on certain proteins. The post-translational modification of cysteine is, however, difficult to follow because it lacks a convenient marker and the oxidative state of cysteine is readily reversed when the cell contents are exposed to extra-cellular oxidizing conditions.
Abnormal cellular proliferation is one type of abnormal cell function. That is a cardinal feature of human malignancy. In recent years there has been great insight into the bio-molecules that regulate cell proliferation and the pathways in which they operate. These bio-molecules have been identified as pharmacological, therapeutic, and/or diagnostic targets for agents which inhibit cellular proliferation. Abnormal cellular proliferation is most often associated with cancer and other hyperproliferative diseases.
Another type of abnormal cell function is resistance to apoptosis. Apoptosis is a form of programmed cell death characterized by membrane blebbing, chromatin margination and breakdown of chromosomal DNA into nucleosome-sized fragments. Loss of apoptosis can lead to diseases such as cancer, autoimmune disease, inflammation, and hyperproliferation disease. Increased apoptosis can lead to neurodegenerative disease and destruction of tissue, as well as cardiovascular damage. Normally, when a cell sustains substantial genetic damage that cannot be repaired through normal DNA repair processes, sensory mechanisms in the cell recognize this and initiate a sequence of events which leads to the death of the cell. Apoptosis results in the death of damaged cells and protects the organism from potentially harmful genetic changes. Inhibition of apoptosis by abnormal expression of an oncogene or loss of a tumor suppressor gene can be closely associated with malignancy. As cells progress from a non-transformed state, through a pre-malignant state to a fully transformed state, the cells lose their ability to undergo apoptosis. Apoptosis is also inhibited by some viral infections.
Discovery of molecules which interfere with or inhibit cellular redox systems satisfies a need in the art by providing new diagnostic or therapeutic compositions useful in the detection, prevention, and treatment of diseases related to abnormal cellular activity (i.e., hyperproliferation or apoptosis).
Proteins and enzymes involved in cellular function provide an attractive site for the development of therapies and diagnostic tools for diseases associated with abnormal cellular function. These agents may serve as therapeutics themselves, or they may increase the efficacy of other therapeutic agents.
The present invention pertains to asymmetric disulfides and focuses on the interaction of these disulfides with cellular signaling pathways having points of redox control. Asymmetric disulfides that inhibit or interfere with cellular redox function have strong potential applications as therapeutic agents, diagnostic tools, chemopreventative agents and chemotherapeutic agents.
The present invention also relates to methods of using asymmetric disulfides for therapeutic and prophylactic treatment of a mammalian host, preferably a human. The disulfides of the present invention may be administered alone or in combination with other therapeutic agents (e.g. other anti-cancer drugs).
The present invention also relates to a composition comprised of an asymmetric disulfide and a pharmaceutically acceptable carrier of said asymmetric disulfide wherein said composition is useful in treating disease. It is preferable that the disulfides of the present invention also prevent the inhibition of apoptosis. The asymmetric disulfides preferably inhibit or interfere with thioredoxin redox system, and more preferably, the disulfides inhibit thioredoxin reductase or thioredoxin. The asymmetric disulfide and pharmaceutically acceptable carrier are preferably formulated or administered in a therapeutically effective amount. The therapeutically effective amount is preferably in a range from about 0.05 mg/kg/day to about 5,000 mg/kg/day, more preferably in a range from about 0.5 mg/kg/day to about 500 mg/kg/day, more preferably in a range of about 1 mg/kg/day to about 50 mg/kg/day, and more preferably yet, the therapeutically effective amount is in a range from about 2 mg/kg/day to about 20 mg/kg/day, and most preferably the therapeutically effective amount is in a range from about 5 mg/kg/day to about 10 mg/kg/day.
The present invention can also be described as a composition for treating a disease wherein the composition is comprised of an asymmetric disulfide in a sufficient dose to be effective in treating said disease. The disease is preferably related to redox function and more preferably related to abnormal cellular proliferation and/or abnormal apoptosis. The disease is preferably selected from the group consisting of cancer, reperfusion injury following ischemia, hepatitis, amyotrophic lateral sclerosis (ALS), neurodegenerative diseases, Alzheimer""s diseases, Autoimmune disease, Sjogren""s syndrome, Lupus, rheumatoid arthritis, HIV, Hermansky-Pudlack syndrome, retinal oxidative damage, retinopathy, skin hyperplasia, aging, ultraviolet damage, wound healing, Crohns"" disease, ulcerative colitis, angiogenesis, uterine disorders, adult respiratory distress syndrome (ARDS), lung disorders, viral and other infections such as herpes virus, pox virus and adenovirus infections, inflammatory conditions, autoimmune diseases such as, systemic lupus erythematosus, psoriasis, inflammatory bowel disease, autoimmune diabetes, immune mediated glomerular nephritis, hyperproliferative diseases such as fibrosis, psoriasis and mycosis fungocides.
This invention also relates to a method of inhibiting growth in a cell, the method being comprised of contacting the cell with an effective amount of an asymmetric disulfide. It is preferable that the asymmetric disulfide be an inhibitor of a thioredoxin/thioredoxin reductase redox system, and even more preferable that the asymmetric disulfide prevents inhibition of apoptosis. The growth in a cell is inhibited by an effective amount of disulfide, and may be additive to the known effectiveness of other active inhibitors.
Another aspect of the present invention is a method of inhibiting tumor growth in vivo comprised of administering an effective amount of an asymmetric disulfide. The method of inhibiting tumor growth involves administering the disulfide in therapeutically effective amounts as described above, and preferably includes mixing the asymmetric disulfide with pharmaceutical acceptable carrier and/or other therapeutic agent.
The present invention can also be described as being drawn to asymmetric disulfides and their formulation in compositions, as well as methods of their use to treat various diseased states. It is preferable in the asymmetrical disulfides of the present invention have respective R groups of divergent functionality. Preferably in the general formula R1xe2x80x94Sxe2x80x94Sxe2x80x94R2 one of R1 or R2 is a good leaving group and the respective other is a poor leaving group. Examples of good leaving groups are compounds which contain electron withdrawing groups or groups which delocalize the electrons of the functional groups (i.e., aromatic and imidazlyl groups). It is preferable that the aromatic groups of the present invention include heteroatoms such as oxygen, nitrogen, and sulfur. Poor leaving groups do not generally have such electron withdrawing characteristics or delocalized electrons. Thus, they do not form substantially stable species when or if they are cleared from the molecule. An example of a poor leaving group is an unsubstituted alkane or alkyl group. The asymmetrical disulfides of the present invention are particularly useful to treat cancers, more particularly, cancers such as myeloma, cervical, lung, gastric, colon, renal, prostate, and breast cancers.
Finally, the present invention relates to a method of treating a diseased state by administering a therapeutically effective amount of an asymmetric disulfide having a predetermined IC50 TR/Trx value, toxicity value, or hydrophilicity as described herein. The asymmetric disulfide preferably has IC50 TR/Trx of less than 150 xcexcg/ml, more preferably, less than 100 xcexcg/ml, and even more preferably, less than 50 xcexcg/ml.